I am not real sure about the whole formula thing...like how much nutrition babies need supplemented when formula fed, etc. Both my babes were breastfed (still nursing 17 month old), so I guess I took the easy way out and just depended on my own milk for most of their nutrition for the first year.
But with that said, I know a lot of babes who are VERY interested in solids at 6-12 months.
My nephew was 25 lbs at 6 months (strictly breastfed) and stayed at that for 6 months, he just sprouted up. At 20 months he may be 28 pounds or so. I ditto the comments about once your baby starts walking that he may slim down a bit. A lot of babies really pork up to have extra chub to burn before they start crawling and walking. I could always tell when my boys and when my friends' kids were getting ready to start crawling or walking because they would get sooooo chunky
Things I fed my kids between 9 months and 15 months were...blueberries, cheerios and other dry whole grain cereals that were easy to gum, small cubes of cheese, 1/2 slice of Ezekial bread (maybe toasted), grapes quartered or eighted (always ate with me watching), gum on a hunk of soft peach, pear, banana (again with me watching, usually peeled), yo baby whole fat yogurt, cooked whole wheat noodles, small pieces of roast or cooked chicken, oatmeal or other whole grain cereal, organic real fruit whole grain cereal bars (very sticky, messy, always ate while confined to high chair
), mandarin oranges, applesauce with no added sugar, some homemade baby food, soft cooked green beans, kidney beans, black beans, northeen beans, peas, cauliflower, brocolli, potatoes, and carrots when cooked in soup or casserole, and some juice, quite diluted, or soy milk. HTH
Personally, I know peds mean well, but they are trained in a different mindset than what I hold, so I don't often find their advice useful. Just a suggestion to always double check a peds advice with your own research